Cheap pulse oximeter and Web Bluetooth


This might not be very practical, or of interest to anyone else, but it combines cheap electronics, healthcare, and web development. Color me behind the times, but I think it’s wild that a web page can connect to my physiology :exploding_head:

I ordered one of these Bluetooth pulse oximeters from China for ~$20 CAD, shipping included, and it arrived within a week. If you’ve ever been to the hospital, they probably put a probe on your finger: That’s a pulse oximeter. The body is transparent to some light frequencies, so just by shining a light through your body (finger), it can see how much blood is saturated with oxygen, and there’s additional information in that signal, too. Your heart rate, for example.

It doesn’t implement a standard Bluetooth profile – it sounds like it just dumps UART data over Bluetooth? – but I modified this Web Bluetooth demo and it works: It displays the pulse rate from the oximeter. It works with Chrome on my phone and on my laptop.

The data from the device includes the SpO2, pulse rate, and the raw photoplethysmogram, from which I hope it’s possible to estimate the respiratory rate (the photoplethysmogram is sensitive to changes in intrathoracic pressure). If you could shine a light through your finger and estimate your respiratory rate, and do it all in a web page, with cheap electronics, that would be neat?

Only vaguely associated, but I heard a podcast recently about building a $400 MRI using the same benign light and holography. Cool stuff!